No Heat On Indesit Washer-dryer (dryer Mode)

As you're an electrician I wont remind you to unplug the machine before working on it.

If a washer-dryer doesn't heat the air (on tumble dry) then the heater is (surprisingly) not actually the main suspect. It's easily identified from the top of the washing machine so look at that first after checking all the contacts and connections of course. There is usually some silver foil wrapping the heating chamber (which contains the element) for insulation. The heating element tags should be easy to spot.

Use a continuity tester to check the resistance -

Pull off the wires to both or at least one of the heating element's tags to prevent false readings

There should be a fair bit of resistance (as in most heating elements) I'd expect a reading of anything between 30 and 50 ohms but usually, a heater either gives a reading or is open circuit (failed)

If you have a meter capable of doing insulation tests at 500v then check the insulation on each tag to earth

A leakage of up to 2 megs is currently (I believe) the accepted limit. Anything much below that is likely to blow fuses and is not safe

If the heater tests out OK, then the TOC's and thermostats are suspect. They should be obvious as all parts for the dryer side of the washer-dryer are on the top of the tub. Check for open circuit on the stats/TOC's. However, although most TOC's (thermal overload cutouts) are closed circuit and go open circuit when blown, it's possible for some makes of washer dryer to use something that's open circuit when OK and close a circuit when activated (although this is pretty uncommon).

Don't forget when testing a tumble dryer or the dryer section on a washer dryer, that the first 10 mins on the dial are no-heat, so ensure you turn it fully on to about half an hour or more or you may cure the fault and not realise it because the heaters won't be energised below 10 minute setting.